Method for the manufacture of elastic rubber tires



K. s. .HALLGREN 2,612,461

METHOD FOR THE MANUFACTURE OF ELASTIC RUBBER TIRES Sept. 30, 1952 s Sheets-Sheet 1 Filed March 21, 1949 p 0, 1952 K. s. HALLGREN 2,612,461

METHOD FOR THE MANUFACTURE OF ELASTIC RUBBER TIRES Filed March 21, 1949 5 Sheets-Sheet 2 p 1952 K. s. IHALLGREN 2,612,461

METHOD FOR THE MANUFACTURE OF ELASTIC RUBBER TIRES Filed March 21, 1949 3 Sheets-Sheet 5 Patented Sept. 30, 1952 UNITED STATES PATENT oFFIcE,

. METHOD FoR THE MANUFACTURE ELASTIC RUBBER TIRES Karl Simon Hallgren, Copenhagen, Denmark Application March 21, 1949, Serial No. 82,599

17 Claims. 1

The present invention deals with the manufacture of elastic caoutchouc tires having a number of internal transverse projections or flanges such as transverse walls dividing the tires up into a number of chambers,

It has previously been known to manufacture such tires by casting them in a mould inwhich, prior to the casting, cores the desired hollows or chambers are placed. The cores consisted of sand or other brittle material which is held together with glutinous material. When removing would remain with the tire, whereupon by striking the tire one could break the cores so that these broken cores could be shaken out of the tire.

It is, however, difficult to empty the chambers completely from the sand or other hard elements of which the cores consist, and as these elements, during the use of the tire, may penetrate into the rubber mass, there is a considerable risk that the tire may be destroyed from the inside. Use has also been made of permanent cores made of metal, but these have a very complicated form and often the single core will have to be composed of a number of separate elements. The result has been that the removal of such cores from the tire has been a most complicated and time consuming procedure.

An important object of the present invention is to do away with these dificulties such as those referred to above. According to the present invention the body of the tire, consisting of a transverse projection or flanges and at least one outer rim connecting the latter as a unit, is cast. The casing is then vulcanized onto the outside of this cast unit. During vulcanization, an inside pressure is maintained in the chambers substantially corresponding to the outer pressure in the mould. In this manner distortion or deformation of the transverse walls as well as penetration of the rubber masses of the casing into the chambers due to difierences in air pressure is prevented.

It will be seen that the application of separate cores of any kind can be avoided, since, according to the present invention, in the construction of the case unit, the chambers between the transverse walls may also be cast in a mould consisting of two parts. This mould has detachable cores which may be inserted to form the said chambers, said cores bein removed from the case unit subsequent to its removal from its mould, but before it is placed in the vulcanization mould. The vulcanization takes place in the mould which is used in casting in the original unit as well as in the mould which is used for the purpose of the tire from the mould the coresfor the formation of vulcanizing the tire casing onto the original unit. For the purposes of clarity the mould for casting the original unit will be termed the casting mould, whereas the mould used in vulcanizing the casing on the unit will be termed the vulcanizing mould. According to a preferablefmethod of employing the invention the unit may be placed in avulcanizing mould consisting of two parts in which the unit is surrounded by'two or more layers of unvulcanized rubber which serve to form the casing of the tire by vulcanization.

Before placing the unit in the vulcanization mould one has to take care that it is properly cemented with a rubber solution in benzol or benzin in order to secure a reliable vulcanization of the casing to the unit.

Both the casting mould and the fixed cores and also the vulcanizing mould may be divided lengthwise at right angles to the section.

In order to facilitate the understanding of the invention the drawings show several embodiments for the moulds to' be used in the method as well as some of the elements cast in these moulds.

The invention will be easily understood by reference to the following specification when read in conjunction with the accompanying drawings,

in which:

Fig. 1 is a perspective view, partly in section, of a castingmould in which the inner-resilient unit of a rubber tire for autos is to be cast;

Fig. 2 is a'perspective view; partly in'section, of a part of the said unit after removal from the mould;

Fig. 3 is a perspective view partly in section of a vulcanizing mould in which the said unit is placed surrounded by unvulcanized rubber sheets, the unit and sheet being shown;

Figs. 4-8 show in perspective, portions ofvarious embodiments of the inner unit;

Figs. 9-12 show various other embodiments of the same invention;

Fig. 13 is a perspective view of a mould with removable cores; and

Fig. 14 is a perspective view of a further embodiment of the cores in the mould shown in Fig. l. i

In a mould, Fig. 1, consistin of two halves I and 2, is'a generally circular space 3; with a number of projecting rectangular cores 4. Each core is divided into two halves like the mould and each half is fixed in one of the mouldvhalves l or 2 with screws 5. I

The lower core part 4 has recesses 6 in which small bridges l are situated. The bridges consist of metal pins. The cores 4 could be replaced by v 3 (acres 42 of the kind shown in Fig. 13. By fixing a screw in a screw hole 43 in the core 42, the core 42 can be drawn out of the mould before opening of the same.- Alternatively, the core 42 could be removed from the cast unit after its removal from the mould.

The cast unit is shown in Fig. 2. It consists of an outer rim 8, and an inner rim 9 which connect a number of transverse walls I0. In the central plane oftheu'nit is formed a thin wall .I l in which small holes I2 are formed as by burning with a glowing pin. The small bridges 1 may, however,

be replaced by thicker bridges 44 (Fig. 14) which 7 x are positioned partly in the recesses in theupper core portion 4, whereby a canal is formed in a wall I (Fig. 2) which will communicate-with the spaces on both sides of the thin wall II When the unit is removed from the mouldfthe small bridges 1 will remain in the unit from which they can be drawn out by means of a pair of nippers or tongs, (not shown) leaving small canals I3 (Fig. 2) penetrating the transverse walls It.

The cast unit is now placed in a vulcanizing mouldfa's 'show'n'in Fig. 3. The two halves l4 and l 5 'of this 'In'ould are first lined withsome unvulcani'z'ed rubber sheets whichjare to form the oasing of the tire. Each side of this lining consists of a rubber sheet as shownat f6 and I1 andthe sheets meet along a "conical surfac I 8 in the vicinity 'of the central plane of the tire. Another sheet l9 forms the the tread. Afsmall rubber band and 2| is situated in each side to surround "a bead core 22 and23. Finally canvas 'is wrapped'ro'und the head. on each side of the rim 9 situated a thin unvulcanized sheet 25 and 2 6. The un'vulcanize'd sheets are cemented with a solution of rubber in petrol or benzol for obtaining a reliable connection with the inner u'nit during the vulcanization to follow.

During the vulcanization an inner pressure is produced in the chambers between the transverse walls I'D by means of compressed air introduced through "a tube 28. The said tube. is 'slidably mounted in a lining 21, and it is pointed so that it can be pressed through the 'rim 9 into one of the chambers. The 9 has on its. inner wall a lining 29 consisting of an unvulcani'z'ed' rubber sheet which will secure an airtight connection r'o'u'nd'the tube 28. w

The air from the tube '28 will now through the canal [3 in the transverse 'wallslu and through the perforations 12in the wall H teeth the chainbers, thereby resisting deformation of the separate transverse walls during the vulcanizing'pr'ocess. Furthermore, counter-pressure is produced to prevent the 'u'nvulcan'ized rubber sheets from being pressed into the chambers-as a consequence of the pressure produced by the compression of the mould halves. I

The unit shown in Fig. 2 may bes'emivulcanized or fullvulcanized in the mould shown in Fig. 1. For instance a vulcanization in about 20 minutes at 140 C. may be considered satisfactory while a vulcanization in a mould shown in Fig. 3 could be terminated in 30 minutesat a somewhat lower temperature, for instance 125 C. These vulcanization times and temperatures depend largely on the con'stituti'on'of the rubber.

In the manufacture of a tire for cars, the, air could be introduced through the tube 28 at a pressure of about 7 kg./cm; but'this pressure should be so chosen that it'will just allow the 'two mould halves to be pressed together. Generally the pressure of the air introducedithrough the tube 28 should-be in the rangeof 5#-20k'g./cm.

The transverse walls In of the unit shown in Fig. 2 could be connected by rims of another shape than the rims 8 and 9. In Fig. 4 the transverse walls 10 are connected by a thin rubber torus 39, passing through the central part of each wall II]. In Fig. 5 the said walls have slits 3| and they are connected by a single rim corresponding tothe rim 9. In Fig. 6, the walls [0 are connected by asingle rim 8 and the walls have perforations 32, while in Fig. 7, :the walls 10 are connected by a rim 33 situated at their upper side. In Fig. 8 is shown a similar rim 33 together with a corresponding rim 34 at the lower side of the walls In having central perforations 35.

' The transverse walls may have a varied thickness whereby the shape of the chambers will vary.

InFig. 9 the chambers 36 are substantially rec-- tangula-r. In Fig.1!) the chambers 3'! are somewhat tapered at their outer ends, and in Figs. 11 and I2 the chambers 38 and 39 are tapered at both ends in that they have a cross section similar to that of a pear. Between't'he chambers 33 and 397sma1l chambers to amt-tare formed, said small chambers having'diainondlike and triangular cross sections. I H g v Having now described my invention, what I claim as new and'desire to secure by Letters Patent is: v

1. Method for thefmanuiacture er resilient rub ber tires having 'a' plurality offtransverse-projections dividing up the tire in chambeisfsaidmeth- 0d comprising the -"steps of casthig a body consisting of projections connected by at least one rim to form a unit, and vumah'izmg a rubber casing to the said unit 11; a meme whee applying an internal pressure "inithe chambers, said pies"- sure substantially correspondingin maame to the outer pressure causedby the application of the mould fduring Wlcanilzla'tidn, whereby any distortion ordeforrna'tion or the transverse walls as well. as penetration or: the "rubber'of t lnecas-v ing into the chambers "during vulcanization to diflerences in air pressure is prevented.

2. A method accQraihg-tc Iai-m 1 wherein the transverse projeetions of the said unit are con:- nected together b'yfa rimriinning alongthemiddie 0f 'the' Cross section. 'slid vulcanizillg Step causing connection of the free ends of themejections with the casing of the tire.

3. A method according to claim 2, wherein thestep of castihgtfhe *umt 'ihclu'de'sf form'ihg the rim at the-smallest diameter "of the tire.

the step of casting -'t rim at the largestdia'mter fof the tire.

5. A method accqra g to claim wherein the step of casting the unit i fclu'des forming the rim at one 'siide 'of the-tire. v

6. A method as claimed in 'claim 2. fwherein I r I ihcludesjforiningjtwor1ms are used fjorfthe assembling ofjthfe p'rojece the step of castingftheunit tions. 7

7. A method, eccordmg rto claim clzwhe em the two rims are cast in'ei'therfside ref a rubber connecting wall; f; V V

8. A 'method according t ciaim 1, wherein "the step of casting "the 'unit includes "forhiing transversewalls together l the outside ends o'ffth'ewaHs andaseclond rim which connect's'the internalends'dfthefwalls. 9. 'A method according-toclaim '1,'inclu'di'ng"the steps of manufacturing the 'unitfinf-af-inoiild hav ing two parts with removably inserted cores for the formation ofthe chambe 'sfia'ndr'eihovihg' th cores from thefmoulde'd unit.

he unit includes rsrhiihg the h with a rimfwliichjcohhe'cts 10. A method according to claim 1, and the step of forming the moulded unit with transverse walls filling up the whole of the cross section of the tire.

11. A method according to claim 10, and the steps of forming the unit in a mould having two parts and transverse core members annularly spaced around the mould, placing core bridges between transverse core members for the formation of passage ways between the chambers, retaining said bridges in the moulded unit when this is taken out of the mould, and later removing said bridges from the transverse walls.

12. A method according to claim 11, and the step of manufacturing the unit with a thin wall in the center plane of the unit across each chamber.

13. A method according to claim 1, and the step of producing the compressed air in the inner of the chambers by means of a tube situated in and leading to at least one of the chambers, all of which chambers communicate with each other.

14. A method according to claim 13, and the step of maintaining the compressed air in the inner of the chambers at such a high value during the vulcanization that the mould halves will just be kept pressed together.

15. A method according to claim 1, and the step of placing the cast unit in a mould consisting of two halves which are lined by unvulcanized rubber sheets, which sheets are to form the casing of the tire at the vulcanizing process.

.6 16. A method according to claim 1, including the step of vulcanizing the casing to the cast unit in a mould which is divided into two halves along the center plane of the tire.

17. A method according to claim 15, and the 7 step of forming the casing by two rubber sheets forming a lining on each side of the circular space REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 684,050 Falconnet et a1 Oct. 8, 1901 882,341 Pepper Mar. 17, 1908 1,351,156 Burnett et al Aug. 31, 1920 1,367,496 Ostberg et al Feb. 1, 1921 1,459,544 McLeroth June 19, 1923 1,637,465 Bierman Aug. 2, 1927 1,812,821 De Mattia June 30, 1931 1,827,668 Musselman Oct. 13, 1931 2,007,825 Day July 9, 1935 2,273,283 Pfeiffer Feb. 17, 1942 2,476,884 Maynard July 19, 1949 

1. METHOD FOR THE MANUFACTURE OF RESILIENT RUBBER TIRES HAVING A PLURALITY OF TRANSVERSE PROJECTIONS DIVIDING UP THE TIRE IN CHAMBERS, SAID METHOD COMPRISING THE STEPS OF CASTING A BODY CONSISTING OF PROJECTIONS CONNECTED BY AT LEAST ONE RIM TO FORM A UNIT, AND VULCANIZING A RUBBER CASING TO THE SAID UNIT IN A MOULD WHILE APPLYING AN INTERNAL PRESSURE IN THE CHAMBERS, SAID PRESSURE SUBSTANTIALLY CORRESPONDING IN MAGNITUDE TO THE OUTER PRESSURE CAUSED BY THE APPLICATION OF THE MOULD DURING VULCANIZATION, WHEREBY ANY DISTORTION OR DEFORMATION OF THE TRANSVERSE WALLS AS WELL AS PENETRATION OF THE RUBBER OF THE CASING INTO THE CHAMBERS DURING VULCANIZATION TO DIFFERENCES IN AIR PRESSURE IS PREVENTED. 